import com.sun.source.tree.Tree;

public class BinaryTree {
    static class TreeNode{
        public char val;
        public TreeNode left;
        public TreeNode right;

        public TreeNode(char val) {
            this.val = val;
        }
    }
    //以穷举的方式 创建一棵二叉树出来
     public  TreeNode createTree(){
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');
        TreeNode G = new TreeNode('G');
        TreeNode H = new TreeNode('H');
         A.left = B;
         A.right = C;
         B.left = D;
         B.right = E;
         C.left = F;
         C.right = G;
         E.right = H;
         return A;


     }
    // 前序遍历
    public void preOrder(TreeNode root){
        if(root == null){
            return;
        }
        System.out.println(root.val + ' ');
        preOrder(root.left);
        preOrder(root.right);
    }
    // 中序遍历
    public void inOrder(TreeNode root){
        if(root == null){
            return;
        }
        inOrder(root.left);
        System.out.println(root.val+' ');
        inOrder(root.right);
    }
    // 后序遍历
    public void postOrder(TreeNode root){
        if(root == null){
            return;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.println(root.val+' ');
    }
}
